It has been estimated that open top railcars transporting coal across the United States from western mines may lose anywhere from 2 to 5% by weight of the coal load by fugitive dust losses during transit.
Not only does this loss of coal represent an economic loss and an environmental contamination issue, particular for rail lines adjacent populated areas, but the collection of coal dust on and around the train tracks is also believed to contribute to train derailments. Thus, the art has long sought ways for reducing the loss of coal from the railcars during transit.
Over the years, a variety of materials have been used and/or considered as a way of reducing the level of fugitive dust associated with the handling of coal. Such fugitive dust-reducing compositions also generally have utility in a variety of other de-dusting applications as well.
Applicants understand that in some cases tall oil pitch emulsions have not been accepted as being suitable for the coal transport application because the conventional emulsions exhibit an excessive level of tack, i.e., stickiness, over a significant range of usage conditions.
One approach for reducing the tackiness of pitch emulsions involves adding a finely divided filler, such as calcium carbonate, as a component of an emulsified pitch. The lower tack pitch emulsion can be made by dispersing the pitch, such as a tall oil pitch or asphalt (bitumen), in water as the continuous phase in the presence of an emulsifying agent and in association with a finely divided filler, especially finely divided calcium carbonate. A variety of materials were identified as suitable emulsifying agents.
Applicants now have surprisingly found that in the presence of certain emulsifying agents, such as the tall oil products and derivatives described in U.S. patent application Ser. Nos. 12/166,387 (U.S. Patent Publication 2009-0065736 A1); 12/023,886 (U.S. Patent Publication 2008-0194795 A1); 11/669,713 (U.S. Patent Publication 2008-0179570 A1) and 12/363,483 filed Jan. 30, 2009 and entitled Oxidized and Maleated Derivative Compositions, it is not necessary to include the finely divided filler material in the emulsified pitch in order to reduce the tack of the pitch emulsions.